The determinations of failure diameters of solid propellants containing predominately ammonium perchlorate and rubber indicated large failure diameters. Thus, it was apparent that testing propellants of large size diameters at full scale would prove to be very expensive, notwithstanding the impact that such testing would have on environmental and safety aspects. Therefore, the need for a coordinated test program was recognized. Consequently the major testing which was completed in the mid-sixties under a program "Standard Propellant Hazards" (SOPHY), which was termed the failure diameter project to end all propellant failure diameter testing, produced such predictable results that the SOPHY predictions can be used to good purpose for many similar propellant formulations to even present times.
More recently, the method of further characterizing explosives and other energetic materials of many varied formulations such as propellant for many end uses comprise applying a shock wave to the energetic material under investigation by means of a known explosive charge. The method typically employs a donor charge in the form of a cylinder or cone which is placed on top of an acceptor charge which is the energetic material being investigated. Attenuators such as cards (plastics or paper) or water is sometimes placed between the donor and acceptor to quantify the succeptability of the acceptor. For example, an explosive pellet of tetryl (donor) is exploded against a sample of a rocket propellant (acceptor) with 1/16 inch cards or discs or plexiglass in between. If the propellant detonates with 50 cards in between but does not detonate with 60 cards in between then it is more sensitive to detonation than a propellant which will detonate at 30 cards but does not detonate at 40 cards.
For certain uses, an explosive charge has to be detonable but the detonable function can be influenced by a shape charge to control the focusing of the energy down the centerline from the shape charge to precisely produce desired results. The resulting structure could yield a penetrator action as needed for antitank-weapons or for a penetrator action as needed for defeating a barrier defense structure.
For certain uses, an energetic propellant grain must have a high specific impulse and good mechanical properties. An example of a method of preparing high burning rate solid propellant grains is disclosed in a commonly assigned U.S. Pat. No. 4,092,189. This patent issued to Robert E. Betts on May 30, 1978 and assigned to the United States of America as represented by the Secretary of the Army, Washington, D.C. is directed to good mechanical properties and high burning rate solid propellant grains prepared from a multimodal blend of at least on ultra-high burning rate propellant that has been cured and ground to a predetermined particle size of from about 100 microns (0.1 millimeter) to about 5 millimeters and at least one uncured propellant composition that has high tensile strength and compatibility with the ultrahigh burning rate propellant and that serves as a binder for the solid propellant grain when cured. Thus, the high burning rate is contributed by the ultra-high burning rate propellant while the high tensile strength is contributed by the propellant formulation having high tensile strength which serves as the binder.
A detonable explosive composition which has high energy would be desirable as the high energy portion of a propellant system; however, the detonable explosive composition portion would have to be attenuated to be safe for use in a propellant system.